Thermo-forming packaging machine and method

ABSTRACT

The invention relates to a thermo-forming packaging machine with a controller, a first forming station for forming a tray into a base film and a second motor-adjustable forming station for forming a lid into a top film. A first detection device detects the marking of the base film for controlling a film advance step of the tray associated with this marking into the sealing station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to European Patent Application Number 13187888.6 filed Oct. 9, 2013, to Elmar Ehrmann entitled “Thermo-Forming Packaging Machine and Method,” currently pending, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a thermo-forming packaging machine and to a method for operating a thermo-forming packaging machine.

BACKGROUND OF THE INVENTION

A thermo-forming packaging machine is known from EP 0 569 993 A1 having a print mark sensor for detecting a print mark of a base film. The print mark sensor is mounted upstream of a forming station and transmits data to a controller which positions work stations such as a forming station, a sealing station and/or a cutting station corresponding to the distance between two successive print marks.

A thermo-forming packaging machine is known from DE 2437127 A1 having a print mark sensor for detecting a print mark of a top film. The print mark sensor is mounted at the film roll-off device of the top film and transmits data to a controller. Workstations such as a forming station, a sealing station and/or a cutting station are movable by motor along a film transport direction and can be positioned according to the distance between two successive print marks. A further print mark sensor can be provided between the sealing station and the cutting station for positioning the cutting station according to the print mark.

DE 101 52 891 A1 discloses a thermo-forming machine with roller chains for transporting a film web. The temperature of the roller chains is detected by sensors and a punching station is moved horizontally with respect to its distance relative to a forming station by a servo motor using a controller to compensate for the changes of the transport steps of the roller chains caused by changing conditions during operation.

EP 1513729 B1 discloses a thermo-forming packaging machine with a forming station for a base and a top film, where both films are shrink films.

It is particularly difficult in a thermo-forming packaging machine, which in addition to the forming station for a base film comprises a forming station for a top film and where both film webs comprise an imprint and a print mark, to unite and to seal the forming of the two film webs in the sealing station accurately in their desired position relative to each other. For example, when manufacturing a package in the shape of a sphere or other geometrical body by use of two half shells each having a circular shell edge, it is important that the two half shells or the sealing edges, respectively, lie superimposed above each other in the sealing station. If both film webs are imprinted, then it is often necessary that the respective imprint on the film webs must during molding of the two half shells additionally be positioned in its location, so that both half shells and their imprints again are exactly in the desired position relative to each other in the sealing station.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a thermo-forming packaging machine which allows a formed tray and a formed top to be united as precisely as possible in a sealing station.

The thermo-forming packaging machine according to one embodiment of the present invention comprises a controller, a first forming station disposed along the direction of production for forming trays into a base film, and a second forming station adjustable by a motor for forming lids into a top film and a sealing station that is stationary in the direction of production for sealing lids onto a plurality of trays. Furthermore, the thermo-forming packaging machine may comprise at least a conveyor chain for transporting the base film in the direction of production. The thermo-forming packaging machine is characterized in that a first detection device can be provided on or in the sealing station for detecting the marking on the base film and to transmit this information to the controller, where the controller may be configured for controlling a film advance step of the conveyor during the transport of the trays, for example, into the sealing station. The trays have, for example, a predetermined position relative to the marking which in turn is known to the controller and is inputted by operating staff or has already been stored in the controller during production of the thermo-forming packaging machine. This brings about the advantage that even existing inaccuracies, stiffness or changes, for example, due to differences in temperature at the advance system, in particular at the advance chain, can be recognized by the first detection device by detecting the marking of the base film and transport of the base film into the sealing station can be effected by the controller such that the trays can be positioned precisely in their position relative to or in the sealing station. The first detection device may also be configured to always detect that marking of the base film which is associated with the trays and thereby to the format that is currently located in the sealing station and to control film advance to the exact position. For this, the first detection device can comprise, for example, a camera and be disposed at a defined distance from the sealing station so that it can, when or directly after specific trays reach the finish line in the sealing station, detect the location of these markings associated with these trays in order to influence or readjust the position of these trays based thereupon when they arrive at the finish line. According to one embodiment of the present invention, the first detection device is then provided on or in the sealing station when it is positioned such that it can detect the position of a marking that is associated with those trays (or a format, i.e., an associated group of trays) that are currently located in the sealing station or that are upstream or downstream of the sealing station by a maximum of one working cycle (i.e. one advance distance).

A second detection device can be provided between the first forming station and the first detection device for detecting the marking of the base film and for transmitting this information to the controller, where the controller may be configured to position the second forming station such that the lids formed into the top film by the second forming station and the associated tray of the base film are sealable in the sealing station in their intended position relative to each other. Precise positioning of the lid in the sealing station can thereby be achieved, and thereby precise positioning to the tray. The lids and the trays can be positioned in a superimposed manner in the sealing station. This is advantageous especially with spherical or egg-shaped packages, for example, having a centrally positioned sealing plane or division, respectively, for being able to produce a shapely package.

The second forming station can be disposed a maximum of five, and preferably a maximum of three film advance steps upstream of the sealing station to minimize tolerances or changes during film transport of the top film up into the sealing station.

In one embodiment, the marking is a print mark on the base film and a third detection device is provided upstream of the first forming station for detecting the print mark of the base film and for transmitting this information to the controller, where the controller is configured to positioning the first forming station in dependence of the print mark of the base film.

In another embodiment, a stretching device for the top film is provided for stretching a printed top film respectively in the direction of transport so that the printed image matches the package later completed.

The stretching device may be disposed in the direction of transport of the top film upstream of the second forming station for stretching the printed image to the desired size already prior to molding (forming) a lid.

The stretching device can comprise a print mark detection device, for example, a print mark sensor for the top film for communicating the position of the print mark to the controller. The controller then additionally may comprise a print mark controller so that the controller can in turn control actuators such as clamping devices and/or drives of the stretching device such that intended stretching of the top film can occur.

In a further embodiment of the thermo-forming packaging machine, a fourth detection device is provided downstream of the sealing station for detecting the marking of the base film or the print mark of the top film and for transmitting this information to the controller, where the controller may be configured to position a cutting station disposed downstream of the sealing station in dependence of the position of the marking of the base film or the print mark of the top film. The position of the cutting station can therewith also be aligned precisely to the package or the sealing seam, respectively, since the sealing seam is predetermined in its position relative to the associated marking. The cutting procedure can thereby be performed without the provision of tolerances and a particularly shapely package with a smallest possible projection of the sealing edge or sealing seam can be produced.

At least one of the detection devices, preferably the first detection device, is a camera for detecting the position of the marking, even during and especially at the end of the film advance step, until the film advance step is completed and the base film was transported precisely into the sealing station.

The marking can be provided as an identification mark on the base film and may be applied using a printing device, or as a molding created into the base film in the forming station, or a punch that is introduced into the base film by use of a punching device. This allows the use of base films that have no pre-produced print marks, and the first forming station can be provided in a stationary manner at the machine frame.

The method according to one embodiment of the present invention for operating a thermo-forming packaging machine with a controller, a first forming station, a sealing station, and a first detection device may provide the following steps:

-   -   molding trays into a base film in the first forming station,     -   performing film advance steps for transporting the base film in         a direction of production,     -   detecting a marking of the base film by use of a first detection         device on or in the sealing station, and passing this         information to the controller,     -   using the controller for controlling the film advance step in         which the trays are transported into the sealing station in         dependence of the position of the marking of the base film.

The trays there have a predetermined relative position to the marking. This brings about the advantage that even existing inaccuracies, stiffness or changes, for example, due to differences in temperature at the advance system, in particular at the advance chain, can be recognized by the first detection device by detecting the marking of the base film, and transport of the base film into the sealing station can be effected by the controller such that the trays can be precisely positioned in the desired position relative to or in the sealing station. The first detection device may also be able to detect that marking of the base film which is associated with the trays that are currently located in the sealing station and to control film advance to the exact position. For this, the first detection device can comprise, for example, a camera and be disposed at a defined distance from the sealing station so that it can, when or directly after specific trays reach the finish line in the sealing station, detect the location of these markings associated with these trays in order to influence or readjust the position of these trays based thereupon when they arrive at the finish line.

In one possible embodiment, the marking is an identification mark that is applied by a printing device onto the base film, or a molding created into the base film in the forming station, or a punch that is punched into the base film by use of a punching device.

In an alternative embodiment, the marking is a print mark on the base film, and a third detection device detects the print mark of the base film upstream of the first forming station and passes this information to the controller for positioning the first forming station in accordance with the detected print mark, where the first forming station is adjustable by motor.

A lid can be molded with a second forming station into a top film for being able to produce a package which has two moldings, where one molding is the tray in the base film and a further molding is the lid in the top film. A sphere-shaped package, centrally divided and sealed together, can thereby be formed in a shapely and thereby attractive manner.

A second detection device being disposed between the first forming station and the sealing station can detect the marking of the base film and passes this information to the controller. The second forming station may be positioned along the direction of transport of the top film by use of the controller in dependence of the position of the marking of the base film that was detected by the second detection device.

In one embodiment of the method, a cutting station is positioned along the direction of production by use of the controller in dependence of the position of the marking of the base film that was detected by the first detection device for obtaining improved positioning of the cut relative to the package or the sealing seam, respectively.

In an alternative embodiment, a fourth detection device is provided on or in the cutting station; and the cutting station is positioned along the direction of production by use of the controller in dependence of the position of the marking of the base film or the marking of the top film that was detected by the fourth detection device. This can achieve precise positioning of the cut relative to the package or for sealing seam, respectively, because any inaccuracies and tolerances in film advance during and until the end of each film advance step can be compensated.

Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawing, which forms a part of the specification and is to be read in conjunction therewith in which like reference numerals are used to indicate like or similar parts in the various views:

FIG. 1 is a schematic side view of a thermo-forming packaging machine according to one embodiment of the present invention, and

FIG. 2 is a schematic sectional view of a first forming station of the thermo-forming packaging machine of FIG. 1 taken generally along line 2-2 in the direction of the arrows according to one embodiment of the present invention.

Same components are throughout the figures designated with the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. For purposes of clarity in illustrating the characteristics of the present invention, proportional relationships of the elements have not necessarily been maintained in the drawing figures.

The following detailed description of the invention references specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The present invention is defined by the appended claims and the description is, therefore, not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

FIG. 1 shows a thermo-forming packaging machine 1 according to one embodiment of the present invention operating intermittently (true-to-cycle) and comprising a machine frame 2 being oriented along a direction of production R. At the beginning of the thermo-forming packaging machine 1 shown at the right in FIG. 1, a roll-off device 3 for a base film 4 can be provided. The base film 4 is fed by use of two advance chains or conveyor chains 30 (see FIG. 2) that are driven by a servo motor M at an advance distance V per work cycle in the direction of production R to a first forming station 5, where the first forming station 5 can produce trays 8 in film 4 by thermo-forming and may be configured to be movable in the direction of production R. Furthermore, a loading stretch 6 for loading a product 7 into molded trays 8 is shown downstream of the first forming station 5. A sealing station 9 for closing the trays 8 filled with product 7 with a top film 10 and a first cutting station 11 being embodied as a transverse cutting device can follow in the further course of production. A second cutting device 12 being disposed downstream of the first cutting device 11 can be embodied as a longitudinal cutting device and separates the packages 13. The first cutting station 11 can also be configured as a complete cutting station that is movable by motor in the direction of production R; then the second cutting station 12 could be omitted. The separated packages 13 are via a conveyor belt 14 transported out of the thermo-forming packaging machine 1.

A first detection device 16 in the form of a camera or a print mark sensor for the sealing station 9 can be arranged in the direction of production R upstream of the sealing station 9. A second detection device 17 in the form of a camera or a print mark sensor for a second forming station 18 molding lids 24 into the top film 10 can be disposed between the first forming station 5 and the first detection device 16. An optionally provided third detection device 15 in the form of a camera or a print mark sensor for the first forming station 5 is arranged in the direction of production R upstream of the first forming station 5.

The top film 10 may be rolled off from a second roll-off device 19 and fed to a stretching device 20 which is disposed in a direction of transport T of the top film 10 upstream of the second twilling station 18. The stretching device 20 can comprise a print mark sensor 21 which passes the location of print marks 10 a of the top film 10 to a controller 22 for the controller 22 to stretch the top film 10 by use of at least one actuator 23 so that a predetermined distance of two respective adjacent print marks 10 a of the top film 10 is obtained.

A plurality of molded (e.g. deep-drawn) trays 8 can be arranged in the base film 4 in the direction of production R, which are in the format of, for example, three trays 8 arranged adjacently to each other (i.e., a three-lane format), and respectively be transported downstream in a cycle intermitting by one tray 8. It is also conceivable, however, that the forming station 5 molds a plurality of rows of trays 8 per cycle disposed behind each other and that this respective format of trays 8, being formed in one work cycle in the forming station 5 into the base film 4, may be further transported in an intermittent (true-to-cycle) manner in the direction of production R. One work cycle also comprises a film advance step by the advance distance V.

In the following, the mode of operation of the thermo-forming packaging machine 1 shall be illustrated in more detail. The base film 4 being rolled off from the roll-off device 3 can be gripped by the advance chains 30 on both sides and fed to the forming station 5. One or more trays 8 are molded (e.g., deep-drawn) in the forming station 5 and at a defined position relative to a marking 4 a of the base film 4 into the base film 4. In order to always obtain this defined position, the position of the marking 4 a can be detected by the third detection device 15, and the forming station 5 may be, prior to each molding operation, adjusted or positioned by motor in direction R as needed. Marking 4 a is there already present as a print mark on the base film 4. Alternatively, the first forming station 5 is mounted in a static manner on the machine frame 2 and the marking 4 a is created only in the forming station 5. For example, the marking 4 a is a formed feature in the base film 4 that can be created by form stamp 31 or a punch which is created by a punching device 32 in, upstream or immediately downstream of the forming station 5 and thereby receives a defined position with respect to the tray 8. It is also conceivable to imprint the mark 4 a in the form of an identification mark by a printing device 33 onto the base film 4.

In the subsequent work cycle, the base film 4 can be further transported with the formed trays 8 intermittingly along the loading stretch 6. The trays 8 are there manually or automatically filled with products 7, for example, using pickers. During the film advance step in which the filled tray 8 is transported into the sealing station 9, the marking 4 a can be, during positioning, detected by the first detection device 16, which may be embodied as a camera, and the current position of the marking 4 a is transmitted to the controller 22 for controlling the length of the current film advance step to the exact target position in the sealing station 9. The distance X of the third detection device 15 from the forming station 5 and thereby from the trays 8 corresponds to the distance X′ of the first detection device 16 from the sealing station 9 and thereby from the trays 8. Negative influences such as tolerances in the advance chain 30, advance chain lengthening due to differences in temperature, or stress due to different base films 4 being transported in a laterally pretensioned manner can be eliminated. The always superimposed position of the sealing seam relative to the tray 8 enables minimization of the width of the sealing seam to a size that is necessary for the particular package 13. In this process, the trays 8 have a least possible distance from one another, which in turn leads to reduction of consumption of film material for the base film 4 and the top film 10, and the appearance of the package 13 itself is improved.

For a package 13 comprising a molded lid 24 being molded by thermo-forming in the second forming station 18 into the top film 10, the second forming station 18 can be positioned by the controller 22 in combination with an electric motor drive, preferably a servo motor or a linear drive, to be able to adjust the molding of the lid 24 at distance Y from the sealing station 9 and thereby from the trays 8. The second detection device 17 provided for this for marking 4 a of the base film 4 is disposed at a distance Y′ upstream of the sealing station 9 along the loading stretch 6 and distance Y′ there corresponds to distance Y. The position of the marking 4 a can be transmitted from the second detection device 17 to the controller 22 which positions the second forming station 18 such that the lid 24 can be precisely united in the sealing station 9 with the corresponding tray 8, the position of which was detected via the marking 4 a, to be able to create a very attractive package 13. The invention has a very positive effect, especially with two hemispherical half shells.

If the lid 24 is to comprise an associated print image that is applied to the top film 10, then the top film 10 can be stretched upstream of the second forming station 18, as repeated print images and print marks 10 a on the top film 10 have a slightly shorter distance from one another than the distance that the lids 24 exhibit between each other in the direction of transport T after molding and which is to correspond to the spacing of the trays 8 in the direction of production R. The stretching process, also referred to as print mark control, can be performed as follows. The print mark sensor 21 detects the print marks 10 a of the top film 10 during the advance motion of the top film 10 in the direction of transport T which is created in that the top film 10 is in the sealing station 9 sealed to the base film 4 and the film advance both transports the base film 4 and rolls off the top film 10 from the second roll-off device 19. The signal of the print mark sensor 21 is transmitted to the controller 22. The controller 22 compares the distance determined between two successive print marks 10 a with the spacing required in the sealing station 9. The controller 22 actuates the actuator 23, which can be implemented as one or several pneumatic cylinders, for clamping the top film 10 between the second roll-off device 19 and the print mark sensor 21 at the end of the current film advance step and for stretching the top film 10 to a certain size in which clamping occurs shortly before the end of the film advance step. Alternatively, a servo motor—not shown—is provided at a clamp to stretch the top film 10 by a linear or rotary motion of the clamp. Tolerances regarding the print image can thereby be corrected and adjusted so that the size and position of the print image are given in a suitable form during molding in the second forming station 18.

To also preform the cutting process precisely, a fourth detection device 25 may be provided for detecting the marking 4 a of the base film 4 which is, for example, a complete cutting station 11 and movable by motor along the direction of production R by use of the controller 22. The fourth detection device 25 has a distance X″, corresponding to distance X and X′, upstream relative to the complete cutting station 11 or the trays 8, respectively. A cut can thereby be performed along the sealing seam that is created in the sealing station 9 and immediately outside of the sealing seam, since positional tolerances of the tray 8 for cutting, namely the cutting blade, can be minimized and any allowance for cutting relative to the sealing seam is not necessary. This leads to further improved appearance of the package 13. The detection devices 15, 16, 17 and 25 can be configured as cameras, in particular as CCD or line scan cameras.

In the embodiment of the thermo-forming packaging machine 1 of FIG. 1, the second forming station 18 is disposed two film advance steps upstream of the sealing station 9 along the direction of transport T of the top film 10 above the base film 4.

In one embodiment, in which the marking 4 a of the base film 4 is a print mark already present on the base film 4, the first forming station 5 is designed adjustable by motor for positioning the forming station 5 in accordance with the print mark 4 a by use of the controller 22. The print mark 4 a is there detected by the third detection device 15 upstream of the first forming station 5 and this information is passed to the controller 22.

From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting.

The constructions and methods described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow. 

What is claimed is:
 1. Thermo-forming packaging machine comprising: a controller; a first forming station disposed along a direction of production for forming trays into a base film; an adjustable second forming station for forming lids into a top film; a sealing station for sealing said trays with said lids; at least one conveyor chain for transporting said base film in said direction of production; and a first detection device provided in or on said sealing station for detecting a position of a marking of said base film and transmitting position information to said controller; wherein said controller is configured to control a film advance step of said conveyor chain during transport of said trays into said sealing station.
 2. Thermo-forming packaging machine according to claim 1, further comprising: a second detection device provided between said first forming station and said first detection device for detecting the position of said marking of said base film and transmitting position information to said controller; wherein said controller is configured to position said second forming station such that one of said lids and an associated said tray are sealable in said sealing station to each other in their intended position.
 3. Thermo-forming packaging machine according to claim 1, wherein said second forming station is disposed no more than five film advance steps upstream of said sealing station.
 4. Thermo-forming packaging machine according to claim 1, wherein said marking is a print mark on said base film, and a third detection device is provided upstream of said first forming station for detecting said marking of said base film and transmitting position information to said controller, wherein said controller is configured to position said first forming station in dependence on the position of said marking of said base film, wherein said first forming station is adjustable in a motorized manner.
 5. Thermo-forming packaging machine according to claim 1, wherein a stretching device is provided for said top film.
 6. Thermo-forming packaging machine according to claim 5, wherein said stretching device in disposed in a direction of transport of said top film upstream of said second forming station.
 7. Thermo-forming packaging machine according to claim 5, wherein said stretching device comprises a print mark detection device for said top film.
 8. Thermo-forming packaging machine according to claim 1, further comprising: a fourth detection device disposed downstream of said sealing station for detecting at least one of said marking of said base film and print mark of said top film and transmitting position information to said controller; wherein said controller is configured to position a cutting station disposed downstream of said sealing station in dependence on the position of at least one of said marking of said base film and said print mark of said top film.
 9. Thermo-forming packaging machine according to claim 1, wherein said first detection device comprises a camera.
 10. Thermo-forming packaging machine according to one claim 1, wherein said marking is provided as at least one of an identification mark creatable by a printing device on said base film, a molding into said base film created in said first forming station, and a punch introduced into said base film by use of a punching device.
 11. Method for operating a thermo-forming packaging machine with a controller, a first forming station, a sealing station, and a first detection device, comprising the steps of: forming trays into a base film in said first forming station; performing film advance steps for transporting said base film in a direction of production; detecting a position of a marking of said base film by use of said first detection device in or on said sealing station, and passing position information to said controller; and using said controller to control said film advance steps in which said trays are transported into said sealing station in dependence of the position of said marking of said base film.
 12. Method according to claim 11, wherein said marking is at least one of an identification mark that is applied by a printing device on said base film, a formed feature that is introduced into said base film in said forming station, and a punch that is created in said base film by use of a punching device.
 13. Method according to claim 11, wherein said marking is a print mark on said base film and a third detection device detects the position of said print mark in said base film upstream of said first forming station and passes position information to said controller for positioning said first forming station according to said detected print mark, wherein said first forming station is adjustable in a motorized manner.
 14. Method according to claim 11, wherein a lid is formed into a top film by a second forming station.
 15. Method according to claim 11, wherein a second detection device being disposed between said first forming station and said sealing station detects the position of said marking of said base film and passes position information to said controller.
 16. Method according to claim 14, wherein said second forming station is positioned along a direction of transport of said top film by said controller in dependence of the position of said marking of said base film that was detected by said second detection device. 